The stone industry can be confusing, sometimes it seems purposely so. There are rules and jargon not everyone is familiar with. We can't break down everything in this blog post but we are going to simplify 3CM and 2CM countertop thicknesses. Generally stone slabs come in three standard thicknesses: 1/2" (1CM) 3/4" (2CM) 1 1/4" (3CM) with nominal deviations. Why does the metric system have to be involved? Well, stone slabs are mined and imported from all over the world and most of the world happens to use this system of measurement. It's annoying but it makes things easier for those in the trade to temporarily put the imperial system on pause when it comes to countertop thicknesses.
1CM is not something you need to worry about, at least not if you are shopping for natural stone, 2CM will be the thinnest a granite or marble is cut so the integrity of the stone is not compromised. That speaks to the fact that thicker=stronger in stone which is why many believe you have to choose 3CM for your countertops. In design it's never fun to say you HAVE to do anything, you absolutely can use 2CM for countertops but there is a smart way to go about it. We will break down all the do's and don'ts of both 2CM and 3CM so you can decide what sounds best for your project.
Large or extended overhangs such as for island seating is something you will want to leave to 3CM. People tend to lean on islands so you will want a thicker profile to handle the weight we would also recommend extra support even with 3CM to protect your investment.
In the image above you can see the longer the overhang the thicker the stone you will need plus added support. The support can be in a hidden bracket, we would recommend the original granite bracket or more decorative supports such as steel or wood corbels.
If an overhang is 5 inches or less you can absolutely get away with using 2CM but in all other scenarios involving overhangs we would recommend 3CM. Generally other sites might put that number at 8 inches and if your kitchen doesn't get much use that might be alright however if you are using heavy pots and pans, have kids that drops lots of things, if its a heavily trafficked area etc. we would recommend being more conservative with any 2CM overhangs.
3CM: Vertical Applications
While it's true the thicker the stone the stronger it is, it also will weigh considerably more. When you are talking horizontal applications such as countertops, flooring or stair treads the weight generally will not be a problem but when we talk about vertical applications such as backsplash, fireplace surround, or waterfall panels weight does need some consideration.
Let's tackle backsplashes first, a slab backsplash is a really great sleek look plus less grout lines means less stubborn stains to worry about. Generally a 2CM or thinner profile stone will be recommended for this kind of application, it will be less weight on the wall, take up less space on the countertops, and best of all cost less. However if you are doing a vanity in a bathroom and you have some 3CM left over from the vanity top it makes complete sense to use it for a 6" backsplash. It's not a large portion of the wall where weight will be affecting anything and it saves you from having to purchase tile or a separate 2CM slab.
For fireplace surrounds we recommend 2CM or thinner but for a raised hearth if people will be sitting on it you will want a thicker 3CM stone.
When it comes to a waterfall panels you can use 2CM or 3CM. Even though it is technically a vertical application 3CM will work here because a lot of the weight will be resting on the floor, it will also be easier to match the island top's thickness if you with a 3CM. However even if you did already go with a 3CM for the island top but are still trying to save money you can absolutely use 2CM for the waterfall panels. You can make 2CM slabs appear thicker by using a compound mitered edge (also known as a built up mitered edge) to match the thickness of the island top. In fact if you wanted to you can use compound mitered edges to make your countertops look even thicker then 3CM for a very impressive and luxurious visual impact.
2CM & 3CM: Best Practices
If you do decide to use 2CM whether for cost reasons or you just like the thinner modern look always install over plywood support, this will also help make up for the slight height difference not using 3CM can make. Never be reluctant to pay for an "extra man charge" trust us no mater if it's 2CM or 3CM these are very heavy stones and you will need a team of skilled people to get it off the truck into your house and onto your countertops without incident this is not an area to cut costs on. If you are choosing 2CM for the cost savings be sure to double check your labor costs if there are a lot of built up mitered edges in your project. Generally it will still cost less than using 3CM however if a shop is busy they may charge more for their time so you will need to factor that into your final decision.
We hope this has helped you make your best informed design decision and if you have any other questions we didn't cover please don't hesitate to reach out to us at firstname.lastname@example.org